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Sillimanite
Sillimanite

Spinel
Spinel



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Sillimanite
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Spinel

Sillimanite and Spinel Optical Properties

1 Optical Properties
1.1 Luster
Vitreous, Subadamantine, Silky
Vitreous
1.2 Pleochroism
Colourless to pale brown to yellow
Absent
1.3 Dispersion
NA0.02
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Translucent
Transparent, Translucent, Transparent to translucent
1.5 Refractive Index
1.653-1.6851.73
Agate Opal
1 3.25
1.6 Optic Character
Not Available
Not Available
1.7 Crystal System
Orthorhombic
Isometric
1.8 Birefringence
0.020-0.022Not Available
Achroite
0 0.296
1.9 Clarity
Transparent
TransparentUlrich Henn and Claudio C. Milisenda

Sillimanite and Spinel Optic Character

Sillimanite and Spinel optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Sillimanite and Spinel Physical Properties like crystallographic symmetry, pleochroism,etc. in the crystal. Some of the optical properties are refractive index, luster, optic character, pleochroism etc. Prominent among these is Sillimanite and Spinel optic character. You might have noticed your gemologist rotating the gemstone while testing it. Rotating a gemstone along its optic axis helps in determining its optic character.

Sillimanite and Spinel Transparency

Similar to their colors, Sillimanite and Spinel transparency can also be used as criteria for their primary identification. Although transparency cannot be the only criteria for gemstone identification, it can efficiently used in gemstone grading. Talking about their transparency, Sillimanite is Translucent and Transparent while Sillimanite is Translucent and Transparent in appearance.